Retired lithium-ion batteries are becoming an important material resource, yet recovering cathode value without dissolution and resynthesis remains challenging. Direct regeneration of spent LiFePO4 is hindered by Li vacancies, Li-Fe anti-site defects, and heterogeneous Fe valences trapped within the olivine lattice. Here we examine defect-to-phase transduction together with carbon-interface reconstruction to address this constraint. Controlled oxidation converts the detectable olivine phase into intermediates containing Li3Fe2(PO4)3 and Fe2O3, removing the inherited olivine site topology. Lithiation and reduction subsequently reconstruct LiFePO4 from these intermediates. Rietveld refinement estimates a decrease in Fe-on-Li site occupancy from 5.72
Lithium primary cells have garnered significant attention owing to long storage life and high safety. However, the capacity degradation law derived from accelerated aging methods is not universally applicable to all operating conditions; thus, lifetime evaluation under calendar aging poses substantial challenges while holding remarkable significance. Herein, comprehensive characterizations were conducted on lithium primary cells subjected to 10-year calendar aging, which aimed to gain a holistic understanding of the degradation mechanism. The results reveal that the surface of the postmortem electrode is covered by complex interfacial species, which exhibit a dual role: They contribute to the low self-discharge rate of cells, and paradoxically, the further deposition of these species at the interfaces between active materials and conductive agents significantly increases the interfacial impedance of electrode, thereby deteriorating the C-rate performance of the cells. This work provides novel insights for the design and development of lithium primary cells.
With the continuous pursuit of high energy density in electrochemical energy storage systems, the thermal safety of lithium-ion batteries has emerged as a critical bottleneck restricting their large-scale application. This article systematically reviews the frontier advances in the field of lithium-ion battery thermal safety, innovatively establishing a comprehensive knowledge framework spanning from microscopic mechanisms to macroscopic system-level protection. First, it provides an in-depth analysis of the triggering mechanisms of thermal runaway and the cross-scale chain reaction evolution pathways, summarizing mechanism-based and data-driven modeling and prediction methods. Second, it focuses on real-time intelligent monitoring and early warning technologies for thermal runaway, constructing a full-process technical system covering “sensing-identification-warning”. In terms of cell-level protection, it systematically outlines the paradigm evolution of cell materials from traditional passive protection toward active-response approaches. Finally, it discusses thermal management and engineering protection strategies at the system integration level, summarizing the critical pathways for enhancing system safety design and failure response capabilities. This review aims to provide a systematic theoretical perspective for resolving the inherent trade-off between energy and safety in high-energy-density batteries and to offer comprehensive theoretical insights and innovative technological pathways for the next generation of energy storage systems.
The common-ion effect of SO4 2- limits the solubility of MnSO4 to <= 1 M in conventional H2SO4 electrolytes, resulting in low specific capacity of manganese (Mn)-based redox flow batteries (RFBs). Although MnO2 semi-solid RFBs are expected to improve the specific capacity, the sluggish electrochemical reaction kinetics leads to low operating current densities (<= 1 mA cm-2). Herein, we employ a reverse-design strategy by introducing additional high-concentration MnO2 into the conventional Mn-based electrolyte. Leveraging the MnO2/Mn2+ electrochemical reaction successfully circumvents the common-ion effect, raising the concentration of soluble Mn species in the electrolyte to 3.76 M and achieving a specific capacity of 156.2 Ah LCatholyte-1 -a 409% increment over reported MnSO4-based electrolytes. Subsequently, the reverse disproportionation of electrolytic MnO2 generated during the second charging cycle shifts the redox mechanism from the MnO2(s)/Mn2+ couple to the solution-phase Mn3+(aq)/Mn2+ pair. This transformation not only elevates the discharge voltage but also enables stable operation at 30 mA cm-2, representing a current density 30-fold higher than reported Mn-based semi-solid RFBs. This work demonstrates a rational design strategy for semi-solid slurry electrolytes to enhance the specific capacity of RFBs, thereby advancing their applicability in grid-scale renewable energy storage.
The rapid expansion of autonomous IoT networks and wearable electronics has intensified the demand for photo-rechargeable zinc-based batteries (PRZBBs). While realizing high overall energy conversion efficiency intrinsically relies on cathode materials capable of multi-electron transfer reactions, current literature largely treats the fundamental electrochemistry of aqueous zinc batteries and the macroscopic engineering of solar-integrated devices as isolated domains. This review bridges this critical gap, offering a unique positioning by establishing a unified analytical framework that directly links fundamental multi-electron redox mechanisms to the dynamic architectural requirements of PRZBBs. Moving beyond a conventional cataloging of material classes, we critically evaluate diverse cathode platforms, including transition metal oxides, Prussian blue analogues, organics, halogens, and sulfur. Our incremental contribution lies in decoupling how specific multi-step reaction kinetics, distinct voltage plateaus, and dominant charge carriers dictate solar cell coupling strategies, particularly concerning maximum power point matching and intermittent charging adaptability. Furthermore, we critically and systematically assess the practical bottlenecks of these chemistries, such as shuttle effects, kinetic limitations, and voltage hysteresis, that hinder scalable integration. Finally, we distill these insights into a prioritized, roadmap-oriented perspective, outlining the short- to long-term engineering and scientific milestones necessary to translate fundamental multi-electron zinc chemistry into next-generation, commercially viable self-powered technologies.
